A large percentage of goods shipped from one point to another point is shipped within a standard size container. This container is approximately 8-10 feet wide and high and approximately 20-40 feet long. These containers are typically packed by the customer of the shipping company and transported by truck to a centralized freight-yard normally located at the dock-side of the shipping vessel. These containers are temporarily stored in the freight-yard until the shipping vessel which is to carry the containers to their destination arrives in port. If these containers were packed arbitrarily within the shipping vessel's hold, the order in which the containers were loaded onto the vessel would not matter. However, in fact, the shipping vessel is loaded in a preplanned order. The preplanned order in which a particular container is loaded into a shipping vessel, typically is a follows:
1) the heaviest containers are placed in the deepest portion of the hold of the shipping vessel in order to maximize the vessel's stability;
2) flammable or explosive cargo are loaded above-deck of the shipping vessel for safety reasons;
3) containers which are needed to be refrigerated are clustered around available sources of electric power; and
4) containers are distributed from the starboard side of the shipping vessel to the portside of the shipping vessel such that the net capsizing torque caused by the containers and other cargo is as close to zero as possible.
The cumulative result of the above-mentioned rules is that the shipping company loading the shipping vessel determines very precisely the loading order of the containers once the shipping vessel arrives in port. Thus, the containers are placed upon the shipping vessel in a very specific and defined order. FIG. 1 shows a typical cross-section of the shipping vessel. Location (101) illustrates the proposed location for Container No. 74168829B weighing 39 tons and containing 1/2" hex nuts which is being shipped to Shanghai by the Chock-Full of Nuts Metal Fastener Company of Terrell, Tex. Furthermore, location (103) illustrates the proposed location for Container No. 61992801C weighing 2.4 tons and containing styrofoam wig stands being shipped to the same port by Airhead Plastic Company of College Station, Tex.
Thus, as can be very dearly seen, the containers need to be placed in the hold in a very specific order to place each container at the correct location. Additionally, once the hold of the shipping vessel has been filled, the hatch of the shipping vessel is closed at deck level, and additional containers are stacked above-deck of the shipping vessel. The loading of containers above-deck begins at the center of the ship and proceeds outwards alternately starboard to port, preserving the ship's stability against capsizing. Additionally, once a stack has begun at a given location by the placement of containers, all of the containers to be loaded in this stack are loaded sequentially because the loading cranes used to load the ship includes controls that automatically return the crane to a preset position so that additional containers are placed at the same preset position; this feature reduces the need for the train operator to manually judge the position by "eyeballing" the location of the stack in order to place subsequent containers. Additionally, the container is loaded bottom-up to conform with the law of gravity.
As the above-description implies, loading of the shipping vessel requires a very specific loading order of containers in order to achieve the abovedescribed placement of containers.
Prior to being loaded onto the shipping vessel, the containers arrive at the dock at different times. Additionally, the space at dock-side for these containers is limited simply because the dock-side space is limited and/or expensive. In order to optimize the limited dock-side space, the containers are packed one on top of another to increase the dock-side effective capacity.
The loading company generally has no control over the order in which the containers arrive, and, as a consequence, the containers could be indiscriminately stacked on one another, up to five containers deep. Very likely, the containers that are to be loaded into the shipping vessel first are actually placed under containers which are to be subsequently loaded. Since as described above, the order that the containers are to be loaded onto the shipping vessel is of paramount importance, a great deal of time and resources are wasted by moving containers to temporary locations, and these moved containers are subsequently loaded in order to load the shipping vessel in the correct order.
It would be advantageous for the loading company if the containers could arrive to the dock in the reverse order which the containers are to be loaded into the shipping vessel. This would result in the containers which are to be loaded onto the ship last, being located at the bottom of each stack of containers. For practical reasons, the loading company cannot control the order that the containers arrive. However, these containers to be loaded onto the ship last need to be placed at the bottom of the stack for the efficient loading. The containers which are to be loaded on the ship first are stacked at the top of each stack. Thus, with respect to the loading order, inverted stacks are required. However, as stated above, the loading company does not have the resources to schedule their arrivals, and the loading company accepts and stores the arriving containers in the order in which they actually arrive.
Furthermore, the containers should not be stacked too high, one on another, since the stability of the stack cannot be maintained once the number of stacked containers reaches a predetermined number. Thus, many shipping companies will only stack a maximum of 3 or 4 containers in order to prevent the pile from falling over and damaging the container and contents of the container. As illustrated in Example 1, three containers are placed on top of each other such that the container to be loaded into the ship first is loaded on top, labeled 1, the container to be loaded onto the ship second is in the middle, labeled 2 and the container to be loaded on the ship third is located on the bottom of the stack, labeled 3. ##STR1##